Also, the Rotary EFX has two parameters to control slow to fast speed.
From the JV1010 HTML manual:

Low Acceleration (Low frequency acceleration)

Adjust the time it takes the low frequency rotor to reach the newly selected speed when switching from fast to slow (or slow to
fast) speed. Lower values will require longer times.

High Acceleration (High frequency acceleration)

Adjust the time it takes the high frequency rotor to reach the newly selected speed when switching from fast to slow (or slow to
fast) speed. Lower values will require longer times.

Mgomes